In a fuel system of vehicle there is typically provided a fuel tank associated with a fuel pump module connected by a fuel delivery line to the fuel rail and injectors of the engine, with a plurality of valve means provided to regulate fuel and vapor flow.
At locations with a hot climate, the fuel in the tank system expands when the drive stops after an operating phase. It is problematic when the fuel expands in the feed line that connects the tank with the combustion engine, resulting in pressure increase in fuel feed line, which may result in fuel leakage or in malfunctioning of the engine. On the other hand, at low environment temperatures and under fuel consumption, pressure within the fuel tank decreases, which may result in deformation or cracking of the fuel tank.
Thus it is a requirement that a fuel system be suited for fuel supply at a relative high flow rate in a direction from the fuel tank to the engine whilst allowing for venting the fuel tank to prevent vacuum in the fuel tank.
Examples of fuel tank valves of the concerned type are disclosed in the following disclosures:
U.S. Pat. No. 5,477,829 discloses a fuel delivery system for a fuel injected automotive internal combustion engine that has a fuel pump mounted within a fuel tank for pumping fuel through a fuel line to an engine mounted fuel rail which delivers fuel to a plurality of fuel injectors. Attached on the output side of the fuel pump in the fuel line is a pressure valve for controlling fuel flow from the pump to the rail and from the rail to the pump. The pressure valve has a housing for containing a check valve, which opens upon the fuel pump delivering a predetermined pressure to the fuel line, and a pressure relief valve, which opens to allow fuel flow from the fuel line to the output side of the fuel pump when the fuel line is over pressurized. The relief valve has a predetermined set point greater than that of the check valve is mounted in parallel therewith so that pressure in the fuel line is maintained at an appropriate level during long deceleration periods, as well as when the engine is off.
U.S. Pat. No. 5,623,910 discloses a combination check and vent valve assembly for an automotive engine fuel system. The valve assembly has a fuel passage through a housing with an inlet communicating with a fuel pump outlet and an outlet to supply fuel to the engine. A check valve is disposed within the fuel passage which is normally closed when the fuel pump is not operating, and will open when the inlet fuel pressure exceeds the outlet fuel pressure. A normally closed vent valve is disposed within the fuel passage upstream of the check valve and serves as a moveable seat for the check valve, which will open when the valve assembly outlet fuel pressure is greater by a predetermined value than the fuel pump outlet pressure to bleed fuel through the passage and to the pump to reduce the outlet fuel pressure to a predetermined minimum pressure.
U.S. Pat. No. 6,352,067 discloses a fuel system pressure valve includes is interposed in a fuel line between a fuel pump and a fuel rail for controlling fuel flow from the pump to the rail and from the rail to the pump. The valve includes a valve housing having a pair of half sections to form a valve chamber. A check valve is mounted in the chamber and is operable to allow fuel flow from the pump to the fuel line upon the fuel pump delivering a predetermined fuel pressure to the fuel line. A pressure relief valve is mounted within the chamber parallel to the check valve and is operable to allow fuel in the fuel line to flow through the housing to the fuel pump upon fuel pressure in the fuel line exceeding a predetermined relief pressure. In addition, a parasitic flow orifice is mounted in fluid communication with the valve chamber and allows fuel in the valve chamber to flow through the orifice to a fuel tank when valve chamber pressure is below a predetermined valve chamber pressure. Fuel is prevented from flowing through the parasitic flow orifice when the valve chamber pressure exceeds the predetermined valve chamber pressure.
U.S. Pat. No. 6,668,802 discloses a valve arrangement is provided for a feed line to supply fuel from a tank to a combustion engine consisting of a valve housing with an inlet channel and outlet channel, and a valve with a movable valve head to seal the outlet channel from the inlet channel, whereby a feed pump is assigned to the feed line, and the valve head is in closed position when there is no feed pressure from the feed pump. The danger of feed line leakage for combustion engines that burn liquid fuel is eliminated using a coaxial second valve using no additional space to solve the problem. The other essentially coaxial valve within the main valve is in open position opposite the feed direction when the pressure at the outlet channel is greater than the feed pressure. The valve arrangement functions as a check valve when the combustion engine is running, and as an overpressure valve when it is off. The solution does not requiring additional installation space, and can be economically integrated into existing fuel systems without any substantial installation effort.
U.S. Pat. No. 6,837,219 discloses a ported pressure relief valve used in an automotive fuel system includes an unrestricted constant bleed orifice for routing pressurized fuel from a fuel pump back to a fuel source when an engine is running. A check valve prevents flow from a fuel system back to the fuel source when the engine is off, so to retain sufficient pressure in the delivery system that the engine will readily start when cranked. A pressure relief valve drains fuel from the delivery system back to the source of fuel in response to a pressure build up in the fuel delivery system above a predetermined pressure level so to prevent an overpressure condition which would otherwise damage the fuel delivery system.
In a no-return (check valve) as well as in other types of fuel systems, it is desirable to reduce the number of fuel passages, which thereby reduces the number of possible failure modes or leak paths. It is also desirable to reduce the number of parts in a fuel system to simplify the assembly process, to reduce cost and to reduce the size and weight of components.
It is therefore an object of the present invention to provide a two way check valve, where flow parameters in each direction are different, said valve having a simple and cheap design.